Thank you very much for all your help, salmon38.

I was planning in the future to drop a different trans in, probably a TH200-4R, but that's looking a little expensive for right now, so I'm thinking a TH350 will be fine and just keep that in.

Is the TH350 a direct replacement for the ST300 in terms of driveshaft and crossmember?

Now it's got me worried as to what exactly the rear-end is...